Magnetic stabilizing means for strip

ABSTRACT

Tapered poles of an electromagnet are positioned adjacent the edges of a magnetic metal strip as it passes from the surface of a coating bath or the like to stabilize the strip against flutter and other lateral stability disturbing influences.

United States Patent Moskowitz et al.

1 51 May9, 1972 [541 MAGNETIC STABILIZING MEANS FOR STRIP [72] Inventors: Isadore Moskowitz; George F. Lemon, Jr.,

both of Baltimore, Md.

[73] Assignee: Bethlehem Steel Corporation [22] Filed: Nov. 23, 1970 [21] Appl. No.: 91,721

[52] U.S.Cl ..118/6, 1 18/33, 118/620, 226/93, 242/752 [51] Int. Cl. ..B05c 11/12 [58] Field of Search ,.118/620, 33, 6', 324/1 NO; 317/1 NQ; 335/209, 284; 242/752; 226/200, 93; l 17/93.2

[56] References Cited UNITED STATES PATENTS 2,141,104 12/1938 Buccicone ..226/93 2,360,097 10/1944 Balthis et a1. ..118/620 X 2,502,770 4/1950 Watson i ..1 18/620 2,731,212 1/1956 Baker 242/752 2,750,461 6/1956 Bunch ..335/284 2,828,467 3/1958 Stauffer. ....335/284 X 2,834,692 5/1958 Tama 118/620 X 3,077,444 2/1963 Hoh .11 18/620 X 3,082,735 3/1963 Vaccaro ..118/33 3,380,686 4/1968 Gaudin ..242/75.2 3,518,109 6/1970 Halley "117/932 Primary E.taminer-Morris Kaplan Armrnqv-1oseph J. O'Keefe 1 ABSTRACT Tapered poles of an electromagnet are positioned adjacent the edges of a magnetic metal strip as it passes from the surface of a coating bath or the like to stabilize the strip against flutter and other lateral stability disturbing influences.

15 Claims, 3 Drawing Figures PATENTEDMM 9:912 3,661,116

SHEETIUFZ I INVENTORS /saaare Mos/row: Geo/ye E Lemon Jr.

PATENTEDMAY 9 I972 SHEET 2 OF 2 IN VENTORS Y M J, m m w Mm A Z a o Mfi we 2 we /6 Y B MAGNETIC STABILIZING MEANS FOR STRIP BACKGROUND OF THE INVENTION This invention relates to the stabilization of metallic strip and particularly to the magnetic stabilization of strip' passing from coating baths.

So-called jet wipers for the wiping of steel strip passing from molten metal coating baths with concentrated streams of gas to remove excess molten metal from the strip surface have come into wide use in recent years. These jet wipers replace the so-called exit rolls which were previously used to establish the thickness of coating on the metal surfaces in molten metal bath type coating operations. Exit rolls contacted the strip on both sides at or close to the point at which the thickness of the coating was established. The exit rolls thus served to guide the strip and prevent disturbing lateral movements of it.

Jet wipers on the other hand constitute a noncontacting type coating thickness determining apparatus which does not provide any lateral support for the strip. Strip contacting guide means such as rolls, furthermore, cannot be used near the jet wipers either as it passes to the wipers or away from the wipers without detrimentally disturbing the still molten coating. In particular the strip passing away from the jet wipers cannot be contacted with any solid supporting means until the coating has solidified or fused. The strip, however, often travels a fair distance before complete solidification takes place. Furthermore, the jet wipers not only do not support the strip but the pressure of the gas jets upon the strip cause buifeting of the strip which results in flutter and twisting of the strip, all of which is detrimental to the formation of uniform coatings. (Flutter may be defined as fairly gross uneven lateral vibrations.) Stabilizing rolls have been located just under the surface of the coating bath as close to the jet wipers as possible to contact the strip and stabilize it, but these rolls have not been entirely satisfactory particularly in suppression of the flutter and twisting of the strip caused by the blast of the jet wipers.

SUMMARY OF THE INVENTION The present inventors have discovered that the strip can be successfully stabilized against flutter and twisting and other disturbing influences as it passes from a coating bath by positioning tapered magnet means adjacent the edges of the strip in the area in which stabilization is desired.

DEFINITIONS In the present application the term longitudinal refers to extending in the direction of the length of strip, transverse refers to a direction to the side of and in the plane of a strip, and lateral refers to a direction perpendicular to the plane of a strip.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of the stabilizer of the invention.

FIG. 2 is a diagrammatic sectional view of the arrangement of the stabilizer of FIG. 1 in a coating line.

FIG. 3 is a section along line 33 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 there is shown a large electromagnet ll comprised of a body portion 13 supported upon a nonmagnetic mount 15 on a base 17. Coils l9 surrounding arms 21 of magnetl I serve to energize a magnetic field across adjustable pole pieces 23 and 25 slidably mounted in nonmagnetic channels 27 supported on brackets 29. The pole pieces 23 and 25 may be conveniently formed, as shown, from laminations of magnetic material 24 preferably surrounded by a confining and protective shield 26 formed from a nonmagnetic material such as copper or brass. The windings of coils 19 are energized by an electrical circuit established via wires 31 and 33 from any suitable power source, not shown.

Pole pieces 23 and 25 are made adjustable by means of a suitable rack and pinion arrangement on their lower surfaces,

not shown, the pinions being in each case mounted on the ends of shafts 35 of gear reducers 37 driven through shafts 39 from motor means 41.

The extreme ends 43 of the pole pieces 23 and 25 are tapered as shown in a modified step design, in the area adjacent to a strip 45 shown in dotted outline passing between them. The tapering of the pole pieces serves to concentrate the magnetic field established through the pole pieces through the strip so as to increase the stabilization of the strip, Preferably the pole pieces will be tapered in a modified wedge shape as shown although many other tapered sections will also be satisfactory such as, for instance, even a round pole face. What must be avoided is a flat pole face of any substantial area facing the strip edges. The long length of the wedge should extend in the same plane as the plane of the strip. The effective face of the wedge facing the strip edge will preferably be not much greater than one quarter inch across for most strips and more preferably will be from approximately the same width as the gage of the strip to about twice the width of the gage of the strip. The ends of the pole pieces will usually be from 4 to 6 inches across in the direction of the plane of the strip. The wider the pole piece face in the plane of the strip the wider will be the area of stabilization of the strip, but the magnetic field through the strip will be more dispersed at any given point for any given size of electromagnet.

In FIGS. 2 and 3 the magnetic stabilizer of FIG. I is shown arranged in combination with a molten metal bath type galvanizing line. A steel strip 45 passes into a pot 47 containing molten zinc 49, around two sinker rolls 51 and 53 shown in dotted outline submerged in the pot 47 and from the surface 49a of the molten zinc to and over a deflector roll 55 some 40 to 60 feet above the zinc surface. Shortly after the strip passes from the surface ofthe zinc bath it passes between two jet wiping nozzles 57 and 59 which direct elongated streams, or curtains, of pressurized gas such as steam against the lateral surfaces of the strip to remove excess molten metal. The steam or like gas striking the strip tends to force it out of line and causes buffeting of the strip which results in flutter and twisting in the strip. A roll such as shown at 61 may be used under the surface of the bath to center the strip as it passes between the jet wipers 57 and 59 but this roll is not effective to prevent all fluttering and twisting. A magnet means 63 of the general design shown in FIG. 1 is therefore positioned adjacent to the jet wipers and preferably slightly above the jet wipers 57 and 59. The magnetic field established between the poles 67 of magnet means 63 is effective to substantially eliminate all flutter and twisting in the strip as it passes between the jet wipers 57 and 59. The magnetic lines of force are concentrated in the metallic strip across the gap between the magnet poles so that the strip is in effect stretched and aligned between the poles of the magnets and is thus held steady. The effect is somewhat like that of a keeper placed between the poles of a permanent magnet to concentrate the magnetic lines of force, except that there is an air gap between the poles of the electromagnet and the strip. The air gap prevents the molten metal coated surface from being marred by the stabilizing means in the relatively long stretch above the jet wipers in which the coating is still molten.

If desired a second stabilizing magnet means may be positioned below the jet wipers to further steady the strip provided there is sufficient clearance between the jet wipers and the surface 49a of the coating bath. In some cases only a single stabilizing magnet means may be positioned below rather than above the jet wipers. Additional stabilizing magnets may also be positioned along the extent of the strip between the jet wipers and the deflector roll 55. Ordinarily, however, a single stabilizer just above the jet wipers is the most satisfactory arrangement with the further possibility of using a second stabilizer just below the jet wipers. The most important consideration is usually to position the magnetic stabilizer close to the jet wipers. In some cases the stabilization of the strip attained from the use of one or two stabilizing magnets will be sufficient so that roll 61 may be completely eliminated, but in other cases it may be desirable to retain the roll 61 to aid in maintaining proper tracking of the strip between the jet wipers. Placement of the stabilizer just above the jet wipers provides stabilization of the strip in an area in which no conventional contacting type guide can be used and also provides a desirable lateral support to the strip on both sides of the jet wipers as the strip extends from the sinker roll 53 and guide roll 61, if such secondary guide roll is used under the surface of the bath, to the magnetic stabilizer 63. The magnetic field does not detrimentally affect the thin coating of still molten coating metal established by passage of the strip through the jet wipers.

Ordinarily both poles of the magnet means will be made adjustable as shown in FIG. 1 so that the proper air gap may be maintained between the strip and the poles of the magnet and a certain tracking of the strip and various widths of strip allowed for. As an alternative, however, the entire magnet means may be made adjustable transversely of the strip in the same plane as the strip. Only one pole piece need then be adjustable. Adjustment of the air gap on one side of the strip will then be made by adjusting the entire magnet means and adjustment of the air gap on the other side of the strip may be made by adjustment of the pole piece on that side.

While the use of the invention has been described in FIGS. 2 and 3 with reference to the stabilization of a steel strip passing from a coating bath through jet wiping devices, being an environment where the stabilizing device has, in fact, been found most useful and novel, it will be realized that the apparatus of the invention can also be adapted for the stabilization of other magnetic strip materials, other shapes of elongated magnetic materials and in other environments than coating operations conducted on such materials.

We claim:

1. Antiflutter and lateral stabilizer apparatus for longitudinally moving small and thin gage magnetic linear material comprising:

a. an established travel path for linear material between rotatable support and guide means, and

b. diametrically opposed first and second tapered magnet means mounted with their narrowest dimension adjacent to the longitudinal edges of said linear material such that the linear material passes through a magnetic field established between said magnet means causing a concentration of the magnetic lines of force in the linear material to stabilize the linear material in said travel path.

2. Stabilizing apparatus according to claim 1 wherein said magnet means are electromagnet means.

3. Stabilizing apparatus according to claim 2 wherein said magnetic linear material comprises strip and sheet material.

4. Stabilizing apparatus according to claim 3 wherein said strip and sheet material are composed principally of steel.

5. Stabilizing apparatus according to claim 4 wherein said magnet means are positioned adjacent to and in line with the edges of said strip and sheet material.

6. Stabilizing apparatus according to claim 5 wherein the magnet means comprise the opposite poles of a single electromagnet means.

7. Stabilizing apparatus according to claim 6 wherein at least one of the poles of said magnet means is adjustable toward and away from the strip edges to aid in adjusting the magnet means to the strip.

8. Stabilizing apparatus according to claim 7 wherein said magnet means is mounted adjacent a strip passing from a molten metal coating bath to stabilize said strip.

9. Stabilizing apparatus according to claim 8 wherein said tapered magnet means are elongated along the axis of a plane disposed in the same direction as the plane of the strip in its travel path.

l0. Stabilizing apparatus according to claim 9 wherein the poles of said magnet means are substantially wedge shaped at least in their portion nearest to the strip.

1 l. Stabilizing apparatus according to claim 9 wherein both poles of said magnet means are adjustable toward and away from said travel path.

12. A hot metal coating apparatus for steel strip comprising:

a. a molten metal bath,

b. guide means for guiding a steel strip through said bath for coating;

c. elongated gas wiping means arranged adjacent to said molten bath to wipe excess molten metal from the surface of said strip as it leaves said molten bath, and

d. electromagnet means having tapered pole pieces elongated in a direction in line with the plane of the strip posi tioned on opposite sides of the strip adjacent the edges thereof and close to the gas wiping means to stabilize the travel path of said strip past said wiping means.

13. Hot metal coating apparatus according to claim 12 wherein the poles of said electromagnet means are wedge shaped in the vicinity of the strip edges.

14. Hot metal coating apparatus according to claim 13 in which said electromagnet poles are positioned adjacent and in line with the strip edges slightly beyond the gas wiping means with respect to the movement of said strip.

15. Hot metal coating apparatus according to claim 14 in which the poles of said electromagnet means are adjustable toward and away from strip edges. 

1. Antiflutter and lateral stabilizer apparatus for longitudinally moving small and thin gage magnetic linear material comprising: a. an established travel path for linear material between rotatable support and guide means, and b. diametrically opposed first and second tapered magnet means mounted with their narrowest dimension adjacent to the longitudinal edges of said linear material such that the linear material passes through a magnetic field established between said magnet means causing a concentration of the magnetic lines of force in the linear material to stabilize the linear material in said travel path.
 2. Stabilizing apparatus according to claim 1 wherein said magnet means are electromagnet means.
 3. StAbilizing apparatus according to claim 2 wherein said magnetic linear material comprises strip and sheet material.
 4. Stabilizing apparatus according to claim 3 wherein said strip and sheet material are composed principally of steel.
 5. Stabilizing apparatus according to claim 4 wherein said magnet means are positioned adjacent to and in line with the edges of said strip and sheet material.
 6. Stabilizing apparatus according to claim 5 wherein the magnet means comprise the opposite poles of a single electromagnet means.
 7. Stabilizing apparatus according to claim 6 wherein at least one of the poles of said magnet means is adjustable toward and away from the strip edges to aid in adjusting the magnet means to the strip.
 8. Stabilizing apparatus according to claim 7 wherein said magnet means is mounted adjacent a strip passing from a molten metal coating bath to stabilize said strip.
 9. Stabilizing apparatus according to claim 8 wherein said tapered magnet means are elongated along the axis of a plane disposed in the same direction as the plane of the strip in its travel path.
 10. Stabilizing apparatus according to claim 9 wherein the poles of said magnet means are substantially wedge shaped at least in their portion nearest to the strip.
 11. Stabilizing apparatus according to claim 9 wherein both poles of said magnet means are adjustable toward and away from said travel path.
 12. A hot metal coating apparatus for steel strip comprising: a. a molten metal bath, b. guide means for guiding a steel strip through said bath for coating; c. elongated gas wiping means arranged adjacent to said molten bath to wipe excess molten metal from the surface of said strip as it leaves said molten bath, and d. electromagnet means having tapered pole pieces elongated in a direction in line with the plane of the strip positioned on opposite sides of the strip adjacent the edges thereof and close to the gas wiping means to stabilize the travel path of said strip past said wiping means.
 13. Hot metal coating apparatus according to claim 12 wherein the poles of said electromagnet means are wedge shaped in the vicinity of the strip edges.
 14. Hot metal coating apparatus according to claim 13 in which said electromagnet poles are positioned adjacent and in line with the strip edges slightly beyond the gas wiping means with respect to the movement of said strip.
 15. Hot metal coating apparatus according to claim 14 in which the poles of said electromagnet means are adjustable toward and away from strip edges. 